The synergies created by a protocol like nostr should be a gigantic driver. I had criticized Damus early on for not mentioning once "nostr" on the website but in the end it doesn't matter. If Damus would change the client to only talk to one company relay, all its users would already have their accounts that would be free of such a limitation. They can get aware of this as late as actual problems arise and that keeps the clients in line. They can try out the limits, maybe a bit of ads and a bit of censorship but if they overdo it, users figure it out and switch at almost zero switching cost as opposed to switching from a platform.